Resistance and ductility of FRP composite hybrid joints

An experimental investigation of the load-bearing behavior and ductility of FRP hybrid double-lap joints composed of both adhesively-bonded and bolted connection parts was conducted. Amongst other things, the effects of the adherends’ fiber architecture (uni- or multidirectional), adhesive type (stiff or flexible), and displacement rate were examined. The resistances of the hybrid joints with flexible adhesive corresponded to the full summation of the resistances of the bonded and bolted connection parts. The ultimate failure loads of these joints were furthermore significantly improved by increasing the displacement rate, while the deformation capacity did not decrease. The hybrid joints with multidirectional adherends and flexible adhesive exhibited high joint efficiencies and excellent ductility and thus may increase the overall safety of redundant engineering structures composed of brittle FRP members. These joints may also fulfill fail-safe conditions as required in European standards.